1. Field of the Invention
The present invention relates to a display driving apparatus and a method for driving a display driving apparatus as well as a display apparatus and a method for driving a display apparatus.
2. Description of the Related Art
There exists a display apparatus that includes a display panel in which current driving-type light-emitting elements (e.g., organic electroluminescence (EL) elements, inorganic EL elements, light-emitting diodes (LED)) are arranged in a matrix manner.
For example, Unexamined Japanese Patent Application KOKAI Publication No. H8-330600 discloses an active matrix-type driving display apparatus that is current-controlled by a voltage signal. This driving display apparatus is structured so that a current control thin film transistor and a switching thin film transistor are provided for each pixel. The current control thin film transistor flows current in an organic EL element when a voltage signal corresponding to image data is applied to a gate, and the switching thin film transistor turns ON or OFF the supply of the voltage signal to the gate of the current control thin film transistor. The driving display apparatus disclosed by Unexamined Japanese Patent Application KOKAI Publication No. H 8-330600 controls the brightness when an organic EL element emits light by controlling a voltage value of the voltage signal applied to the gate of the current control thin film transistor.
However, a threshold voltage of a transistor generally varies as time passes. Thus, in the case of the driving display apparatus of Unexamined Japanese Patent Application KOKAI Publication No. H 8-330600, a threshold voltage of a current control thin film transistor for supplying current to an organic EL element varies as time passes, which causes a variation in a value of current flowing in the organic EL element. As a result, there is a risk that brightness during the light emission by the organic EL element may vary.